The present invention relates generally to computer pointing devices, and more particularly, to an optical mouse having an integrated image sensor for passively receiving ambient images and for translating motion in the received images to a corresponding movement in a cursor.
Various types of pointing devices are used as input devices that allow a user to manipulate a cursor of a computer. In laptop computers, a capacitive touch pad is commonly used to manipulate the cursor. For desktop computers, the ubiquitous computer mouse constitutes the large majority of pointing devices. The mouse allows for cursor manipulation on a visual display screen of a personal computer or workstation, for example. Cursor manipulation includes actions such as rapid relocation of a cursor from one area of the display screen to another area or selecting an object on a display screen.
In a prior art xe2x80x9croller ballxe2x80x9d mouse, a user controls the cursor by moving the mouse over a surface, such as a mouse pad, so that the cursor moves on the display screen in a direction and a distance that is proportional to the movement of the mouse. The roller ball mouse, however, has drawbacks associated with many other devices that have mechanical parts. Namely, over time the mechanical components wear out, become dirty, or simply break down so that the cursor can no longer be accurately manipulated, if at all.
Recently, xe2x80x9copticalxe2x80x9d mice that use image sensors have been developed. For example, U.S. Pat. No. 6,256,016 describes an optical mouse that produces a collimated beam of light that illuminates a surface upon which the mouse rests. An image sensor receives the reflected images of the surface as the mouse is traversed across a surface. The changes in successive reflected images are then interpreted as mouse movement, which is then correlated to a desired cursor movement. However, this type of mouse must be used in connection with a surface upon which the collimated beam of light may reflect. Thus, the mouse typically must be in close proximity to a surface because of its need to capture a large amount of reflected light. Additionally, the optical lens system used in the mouse of the ""016 patent is adapted to only convey a magnified image of a surface that is in close proximity to the mouse.
Similarly, in U.S. Pat. No. 6,172,354, an image sensor is used to receive light reflected off of a surface. The mouse incorporates a light source that illuminates the surface. The light reflected from the surface is collected by the image sensor as an image. Motion is detected by comparing successive images. However, like the ""016 patent, the mouse typically must be in close proximity to a surface. Another example of such a close proximity mouse is shown in U.S. Pat. No. 6,281,882.
The ""016 patent, the ""882 patent and the ""354 patent are referred to herein as close proximity active optical mice. This is because the mice provide their own interrogating light source and the mice must be in close proximity to a surface (on the order of centimeters or less) in order to be operable. However, these characteristics have drawbacks of increased power consumption and limited operating environment, e.g., the requirement for a convenient and smooth surface.